← Back to Gallery

Off the Beaten Path: Preliminary Results of Reconnaissance Paleoseismic Surveys in Remote Alaskan Lakes

South-central Alaska contains hundreds of remote lakes that cannot be accessed by road but are nevertheless in locations that experience strong ground motions related to Alaska-Aleutian plate boundary seismicity. To facilitate scientific investigations of these remote lakes, the U.S. Geological Survey (USGS) developed a highly portable surveying platform (including transportation via float plane), capable of collecting both high-resolution sub-bottom and multi-beam bathymetry data, as well as ~2m long percussion-driven gravity cores. This study will show preliminary results from two remote lakes, Chelatna Lake located ~150 km north of Anchorage and Allison Lake located south of Port Valdez.

Chirp and bathymetry data in both lakes show evidence for widespread slope failures, including a large 4+ meter thick mass transport deposit (MTD) that extends across the entire lake basin in Chelatna Lake. Sediment cores contain varved stratigraphy (i.e., annual laminations), which are interrupted by silty-sand fining upwards event deposits, interpreted as either seismically or climatically generated turbidites, as well as some tephras. Radionuclide age models (i.e., Cs137/Pb210) suggests that both lakes have recorded historical earthquakes including the 1964 Mw 9.2 Great Alaska Earthquake. The sediment record at Chelatna Lake contains evidence for up to 23 earthquakes in the last ~1800 years. The combination of varved stratigraphy (with potentially annual age resolution), the sensitivity to both historical earthquakes and climate events, together with evidence for older (likely) earthquake-triggered MTDs, motivates expanded coring operations at both lakes. In the Summer of 2024, a collaboration between Northern Arizona University and the USGS will deploy a UWITEC hybrid coring platform capable of recovering 12-18m long piston cores. Cores of this length have the capability of recovering long records that may span many earthquake cycles and extend the climate proxy record to the early Holocene or beyond.

Session: From Faults to Fjords: Earthquake Evidence in Terrestrial and Subaqueous Environments [Poster Session]

Type: Poster

Room: Exhibit Hall

Date: 5/1/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Drake Singleton

Student Presenter: No

Additional Authors